Pets can catch COVID-19 from their owners
While there is no evidence so far that humans con contract COVID-19 from animals, experts have said it may be possible, as the virus does not change between species. In their study, the team analysed households in which pets developed respiratory symptoms at the same time as their humans were suffering from coronavirus.
'These preliminary results suggest that a substantial proportion of pets in households of persons with COVID-19 become infected,' said paper author and veterinary pathologist Dorothee Bienzle of the University of Guelph, Canada.
In the study, people who owned a cat or dog — and in one case a ferret — and had been given a diagnosis of SARS-CoV-2 were invited to have their pet swabbed. If humans were outside the two-week window of suspected infectiousness, antibody testing was offered which looked for recent or past infection, using so-called IgM and IgG antibodies, respectively.
Out of the 17 cats, 18 dogs and one ferret, all cats were tested and none bar one proved infectious, but some showed signs of having been infected. Ferrets and related species like mink are highly susceptible to infection, the researchers noted.
'All cats with an indeterminate PCR or positive antibody results were reported to have had respiratory and/or other illness by their owners around the time of the owner's COVID-19 infection,' said Professor Bienzle. '20 per cent of dogs had positive IgG antibody results — indicating past infection — and one of these was reported to have had an episode of respiratory disease.'
However, she added, 'no dogs had positive IgM results, which would have indicated more recent infection.' 'Eligible participant number was limited by relatively low human transmission rates in the study area,' Professor Bienzle said.
However, she noted, 'these preliminary results suggest that a substantial proportion of pets in households of persons with COVID-19 end up developing antibodies.' 'Due to the narrow window of time available to detect a current infection in pets — especially if their owner is still sick and isolating — blood testing the animal at a later time to check for previous infection is preferable for assessment of transmission.'
'Transmission from mink to humans has been reported on mink farms with a high proportion of infected animals maintained in close quarters and cared for by humans,' she continued. 'Transmission from pets to humans has not been reported, but since the virus changes minimally or not at all after transmission from humans to animals, such reverse transmission may occur.'
Professor Bienzle and her colleagues have encouraged people with coronavirus to stay away from both other people and their pets. 'There is sufficient evidence from multiple studies, including ours, to recommend that SARS-CoV-2 infected persons should isolate from people and animals,' she said.
The full findings of the study were presented at the European Society of Clinical Microbiology and Infectious Diseases Conference on Coronavirus Disease, which is being held virtually from September 23–25, 2020.
'Preliminary results made available at conferences before larger more detailed peer review studies are published and replicated are useful to stimulate discussion and further work, but at this stage are just that: preliminary results,' said veterinarian Tim Morris of the University of Nottingham, who was not involved in the study. 'Constructive challenge should then begin as this abstract is presented, with questions including on how the antibody results compared with those taken before COVID-19 was first reported and if the antibody tests are specific to COVID.'
The team, he added, must also 'fully exclude other animal coronaviruses and [...] other causes of respiratory infection in cats.' 'As such these results should not be over-interpreted and so cause unwarranted alarm, particularly as currently there is no evidence reported of contagious SARS-CoV-2 transmission from pets to people.'